My 2.5 year old son loves to be skin on skin with everyone why is that? Is in normal for a 2 inahalf year old?

He has a 8 year old cousin that he would run up to and take off his shirt just to try to rub his tummy on him and would follow him like a puppy dog. If his grandmother is wearing shorts he would lift up his shirt and put his tummy right on her leg I am not sure how normal is this I understand it is good for newborns to have skin on skin with the parents but a two year old. I don't understand please help.